1. Field of the Invention
This invention relates to a battery pack, which may be used for PDAs (Personal Digital Assistants), for instance. More specifically, the present invention relates to a battery pack having a plate-shaped resin-formed body for dividing an internal space of the battery pack into two spaces in a thickness direction so that a battery is received in one internal space, and a wiring substrate having a control circuit mounted thereon is placed in the other internal space, thereby providing the battery pack, which may securely hold an input/output circuit or the like for a memory card in a limited space in the battery pack, while ensuring that a sufficient insulation is provided to the battery. In addition, the present invention also relates to a battery pack having, along the battery, a first wiring substrate having electronic components surface-mounted on a battery side-face thereof and a second wiring substrate having electronic components surface-mounted on the opposite face to the battery side-face of the first wiring substrate while having no surface-mounted electronic component on a battery side-face thereof, thereby providing the battery pack, which may minimize an increase of a thickness thereof so as to serve also as an interface such as an interface for IC cards.
2. Description of the Related Art
Personal mobile information terminals conventionally have been used to enable mobile viewing of various pieces of information stored in a computer. Thus, the personal mobile information terminals have been downsized enough to be conveniently portable for a user and are recently designed to be thinner so as to be storable in a breast pocket or the like.
For this reason, a recent downsized mobile information terminal has a replaceable battery pack that provides a driving force thereof. The battery pack is replaced with another one at need to prevent the information mobile terminal from becoming inoperable due to a dead battery. In addition, the battery pack is also designed to be thinner in order not to lose a portability of the mobile information terminal connected therewith.
Some of the downsized mobile information terminals as described above are connectable with various information apparatuses, and as a result, may provide an increased number of mobile applications by a use thereof, thereby further increasing usability thereof.
A downsizing of this kind of mobile information terminal, however, involves a disadvantage of a limitation on a space, in which interfaces connectable with various apparatuses are received, resulting in a limited number of apparatuses connectable with this kind of mobile information terminal.
One of approaches for eliminating the above disadvantage is to allow the battery pack to serve also as this kind of interface. This approach is supposed to provide this kind of mobile information terminal with an increased number of connections to various apparatuses as compared with a case of conventional approaches.
Specifically, assume that the battery pack of the mobile information terminal is designed to be connectable with a small-sized memory card so that the memory card connected to the battery pack may be accessed for personal information or the like, for instance. When the battery pack is attached to the mobile information terminal, a side face or the like of the battery pack is exposed to the outside. To provide a connection with the memory card, an opening for inserting the memory card is provided in a side face of the battery pack, and an input/output circuit for connecting the memory card with the mobile information terminal is also provided in the battery pack, thereby allowing the memory card to be available through the battery pack. An IC card having a shape of a credit card can also be used in place of the above memory card.
In this kind of connection for using the battery pack as an interface to the memory card or the IC card, however, this kind of battery pack is required to securely hold the input/output circuit or the like as described above in a limited space of the battery pack while ensuring that a sufficient insulation is provided to a secondary battery. Furthermore, due to a demand for the thinner mobile information terminal as described above, it is also necessary for the battery pack to minimize an increase of a thickness thereof, even when the battery pack is designed to serve also as the interface for the IC card and the like.